1. Field of the Invention
The present invention relates generally to branch pipe lining techniques, and more particularly, to a branch pipe liner bag for lining inner walls of branch pipes. The present invention is also directed to a pipe lining method which is implemented using the branch pipe liner bag and a main pipe liner bag.
2. Description of the Related Art
When an underground pipe, such as pipelines and passageways, becomes defective or too old to perform properly, the pipe is repaired and rehabilitated without digging the earth to expose the pipe and disassembling the sections of the pipe. This non-digging method of repairing an underground pipe has been known and practiced commonly in the field of civil engineering. The pipe lining method utilizes a tubular pipe liner bag made of a resin-absorbent material impregnated with a hardenable resin, and having the outer surface covered with a highly air-tight plastic film. The tubular pipe liner bag is inserted into a pipe to be repaired by means of a pressurized fluid such that the pipe liner bag is turned inside out as it proceeds deeper in the pipe. Hereinafter, this manner of insertion shall be called "everting". When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the pipe, the everted tubular liner is pressed against the inner wall of the pipe by a pressurized fluid, and the tubular flexible liner is hardened as the hardenable resin impregnated in the liner is heated, which is effected by heating the fluid filling the tubular liner bag. It is thus possible to line the inner wall of the defective or old pipe with a rigid liner without digging the ground and disassembling the pipe sections.
The foregoing pipe lining method can be similarly applied to the lining of a main pipe of sewerage pipes or the line and a branch pipe branched off the main pipe.
Conventionally, a branch pipe liner bag for lining a branch pipe, as illustrated in FIG. 20, has been proposed. Specifically, FIG. 20 is a partially exploded perspective view illustrating a conventional branch pipe liner bag 101 which has a tubular resin-absorbent material 104 made of unwoven fabric, such as polyester or the like, having its outer surface covered with a highly air-tight plastic film, with an unhardened liquid hardenable resin impregnated in the tubular resin-absorbent material 104.
The tubular resin-absorbent material 104 has one end turned around to form a flange 105 which is curved to substantially match the curvature of a main pipe 110 (see FIG. 21), later described, and has the outer diameter larger than the inner diameter of a branch pipe 111 (see FIG. 21). The flange 105 holds the foregoing curved shape with a hardened hardenable resin impregnated therein.
Next, a pipe lining method using the branch pipe liner bag 101 of FIG. 20 will be described below with reference to FIGS. 21-23.
FIGS. 21-23 are cross-sectional views illustrating the pipe lining method in the order of steps. Referring first to FIG. 21, there are illustrated a main pipe 110 and a branch pipe 111 branched off the main pipe 110 and having a diameter smaller than that of the main pipe 110. Within the main pipe 110, a work robot 112, which had previously been assembled on the ground, a pressure bag 113, a branch pipe liner bag 101, and so on have been introduced for lining operations.
A set nozzle 116 is attached to a head 114 of the work robot 112. The flange 105 of the branch pipe liner bag 101 is securely set on the set nozzle 116, while the remaining portion of the branch pipe liner bag except for the flange 105 (uneverted portion) is accommodated in the pressure bag 113 as illustrated.
The flange 105 of the branch pipe liner bag 101 is positioned at a branch pipe opening 110a of the main pipe 110, while monitoring the situation inside the main pipe 110 and the branch pipe 111 on the ground through a TV camera 115 installed on the work robot 112 and a TV camera 140 introduced into the branch pipe 111. Subsequently, the head 114 of the work robot 112 is moved upwardly to press the flange 105 of the branch pipe liner bag 101 onto the periphery of the branch pipe opening 110a of the main pipe 110 to provide a close contact between the flange 105 and the periphery of the branch pipe opening 110a.
Next, a compressor, not shown, installed on the ground is driven to supply compressed air to the pressure bag 113 through an air hose to cause the branch pipe liner bag 101, receiving the pressure of the compressed air, to evert and extend toward the ground in a direction indicated by an arrow, as illustrated by broken lines in FIG. 21.
After the branch pipe liner bag 101 is inserted inside out into the branch pipe 111 over the entire length thereof, the hardenable resin impregnated in the branch pipe liner bag 101 is hardened by an arbitrary method, with the branch pipe liner bag 101 remaining pressed onto the inner wall of the branch pipe 111, whereby the inner wall of the branch pipe 111 is lined with the hardened branch liner bag 101. In this way, the branch pipe 111 is repaired.
After the lining of the branch pipe 111 is completed, the main pipe 110 is next lined in the following manner.
As illustrated in FIG. 22, a main pipe liner bag 125 is inside out inserted into the main pipe 110 by a pressure of compressed air. It will be understood that the main pipe liner bag 125 is fabricated in a similar manner to the branch pipe liner bag 101 and includes a tubular resin-absorbent material impregnated with a hardenable resin and having at least the outer surface covered with a highly air-tight plastic film.
When the main pipe liner bag 125 has been inserted inside out into the main pipe 110 over the entire length thereof, the hardenable resin impregnated in the main pipe liner bag 125 is hardened by an arbitrary method with the main pipe liner bag 125 remaining pressed onto the inner surface of the main pipe 110, whereby the inner surface of the main pipe 110 is lined with the main pipe liner bag 125. In this way, the main pipe 110 is also repaired. It should be noted that when the main pipe liner bag 125 is hardened, the flange 105 of the branch pipe liner bag 101 is joined with the main pipe liner bag 125 so as to simultaneously harden a hardenable resin attached to the flange 105 of the branch pipe liner bag 101.
After the lining of the main pipe 110 is completed as described above, a cutter 138 mounted at the front end of the work robot 137, introduced into the main pipe 110, is driven to rotate to cut the main pipe liner bag 125 covering the branch pipe opening 110a, while monitoring the situation inside the main pipe 110 through the TC camera 139 installed on the work robot 137. In this way, the branch pipe 111 is open to the main pipe 110 so that the branch pipe 111 is placed in communication with the main pipe 110.
The conventional branch pipe liner bag 101, however, has a problem with respect to the flange 105. Specifically, the flange 105 is previously hardened and is not impregnated with an unhardened hardenable resin. While a portion of the hardenable resin oozing out of the main pile liner bag 125 is attached to the flange 105 and hardened thereon to join the flange 105 with the main pipe liner bag 125, such a small amount of hardenable resin is not sufficient to ensure the integration of the flange 105 and the main pipe liner bag 125. Such insufficient joining often causes a gap to be formed between the flange 105 and the main pipe liner bag 125, and moreover, underground water or the like may intrude into the main pine 110 through the gap.
Additionally, in the operation using the cutter 138 to cut a portion of the main pipe liner bag 125, since a definite mark indicative of a cut portion is not provided for facilitating the cutting operation, the positioning of the cutter 138, which must be achieved through the monitoring of the TV camera 139, is quite difficult, and therefore an accurate cutting operation is hardly expected.